idnits 2.17.1 draft-ietf-mpls-tp-ethernet-addressing-07.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- No issues found here. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (April 08, 2013) is 4029 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) -- Possible downref: Non-RFC (?) normative reference: ref. 'EUI-64' == Outdated reference: A later version (-08) exists of draft-ietf-mpls-gach-adv-06 -- Possible downref: Non-RFC (?) normative reference: ref. 'LLDP' Summary: 0 errors (**), 0 flaws (~~), 2 warnings (==), 3 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 MPLS D. Frost 3 Internet-Draft S. Bryant 4 Intended status: Standards Track Cisco Systems 5 Expires: October 10, 2013 M. Bocci 6 Alcatel-Lucent 7 April 08, 2013 9 MPLS-TP Next-Hop Ethernet Addressing 10 draft-ietf-mpls-tp-ethernet-addressing-07 12 Abstract 14 The Multiprotocol Label Switching (MPLS) Transport Profile (MPLS-TP) 15 is the set of MPLS protocol functions applicable to the construction 16 and operation of packet-switched transport networks. This document 17 presents considerations for link-layer addressing of Ethernet frames 18 carrying MPLS-TP packets. 20 Status of This Memo 22 This Internet-Draft is submitted in full conformance with the 23 provisions of BCP 78 and BCP 79. 25 Internet-Drafts are working documents of the Internet Engineering 26 Task Force (IETF). Note that other groups may also distribute 27 working documents as Internet-Drafts. The list of current Internet- 28 Drafts is at http://datatracker.ietf.org/drafts/current/. 30 Internet-Drafts are draft documents valid for a maximum of six months 31 and may be updated, replaced, or obsoleted by other documents at any 32 time. It is inappropriate to use Internet-Drafts as reference 33 material or to cite them other than as "work in progress." 35 This Internet-Draft will expire on October 10, 2013. 37 Copyright Notice 39 Copyright (c) 2013 IETF Trust and the persons identified as the 40 document authors. All rights reserved. 42 This document is subject to BCP 78 and the IETF Trust's Legal 43 Provisions Relating to IETF Documents 44 (http://trustee.ietf.org/license-info) in effect on the date of 45 publication of this document. Please review these documents 46 carefully, as they describe your rights and restrictions with respect 47 to this document. Code Components extracted from this document must 48 include Simplified BSD License text as described in Section 4.e of 49 the Trust Legal Provisions and are provided without warranty as 50 described in the Simplified BSD License. 52 1. Introduction 54 The MPLS Transport Profile (MPLS-TP) [RFC5921] is the set of protocol 55 functions that meet the requirements [RFC5654] for the application of 56 MPLS to the construction and operation of packet-switched transport 57 networks. The MPLS-TP data plane consists of those MPLS-TP functions 58 concerned with the encapsulation and forwarding of MPLS-TP packets 59 and is described in [RFC5960]. 61 This document presents considerations for link-layer addressing of 62 Ethernet frames carrying MPLS-TP packets. Since MPLS-TP packets are 63 MPLS packets, existing procedures ([RFC3032], [RFC5332]) for the 64 encapsulation of MPLS packets over Ethernet apply. Because IP 65 functionality is only optional in an MPLS-TP network, IP-based 66 protocols for Media Access Control (MAC) address learning, such as 67 the Address Resolution Protocol (ARP) [RFC0826] and IP version 6 68 Neighbor Discovery [RFC4861], may not be available. This document 69 specifies the options for the determination and selection of the 70 next-hop Ethernet MAC address when MPLS-TP is used between nodes that 71 do not have an IP dataplane. 73 1.1. Terminology 75 Term Definition 76 ------- --------------------------- 77 ARP Address Resolution Protocol 78 G-ACh Generic Associated Channel 79 LSP Label Switched Path 80 LSR Label Switching Router 81 MAC Media Access Control 82 MPLS-TP MPLS Transport Profile 84 Additional definitions and terminology can be found in [RFC5960] and 85 [RFC5654]. 87 1.2. Requirements Language 89 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 90 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 91 document are to be interpreted as described in [RFC2119]. 93 2. Point-to-Point Link Addressing 94 When two MPLS-TP nodes are connected by a point-to-point Ethernet 95 link, the question arises as to what destination Ethernet Media 96 Access Control (MAC) address should be specified in Ethernet frames 97 transmitted to the peer node over the link. The problem of 98 determining this address does not arise in IP/MPLS networks because 99 of the presence of the Ethernet Address Resolution Protocol (ARP) 100 [RFC0826] or IP version 6 Neighbor Discovery protocol [RFC4861], 101 which allow the unicast MAC address of the peer device to be learned 102 dynamically. 104 If existing mechanisms are available in an MPLS-TP network to 105 determine the destination unicast MAC addresses of peer nodes -- for 106 example, if the network also happens to be an IP/MPLS network, or if 107 Link Layer Discovery Protocol (LLDP) [LLDP] is in use, or if it 108 implements the procedures in Section 4 of this document -- such 109 mechanisms SHOULD be used. The remainder of this section discusses 110 the available options when this is not the case. 112 Each node MAY be statically configured with the MAC address of its 113 peer. Note however that static MAC address configuration can present 114 an administrative burden and lead to operational problems. For 115 example, replacement of an Ethernet interface to resolve a hardware 116 fault when this approach is used requires that the peer node be 117 manually reconfigured with the new MAC address. This is especially 118 problematic if the peer is operated by another provider. 120 Another approach which may be considered is to use the Ethernet 121 broadcast address FF-FF-FF-FF-FF-FF as the destination MAC address in 122 frames carrying MPLS-TP packets over a link that is known to be 123 point-to-point. This may, however, lead to excessive frame 124 distribution and processing at the Ethernet layer. Broadcast traffic 125 may also be treated specially by some devices and this may not be 126 desirable for MPLS-TP data frames. 128 In view of the above considerations, the approach which SHOULD be 129 used, is therefore to configure both nodes to use the method 130 described in this document which uses, as a destination MAC address, 131 an Ethernet multicast address reserved for MPLS-TP for use over 132 point-to-point links. The address allocated for this purpose by the 133 Internet Assigned Numbers Authority (IANA) is 01-00-5E-90-00-00. An 134 MPLS-TP implementation MUST process Ethernet frames received over a 135 point-to-point link with this destination MAC address by default. 137 The use of broadcast or multicast addressing for the purpose 138 described in this section, i.e. as a placeholder for the unknown 139 unicast MAC address of the destination, is applicable only when the 140 attached Ethernet link is known to be point-to-point. If a link is 141 not known to be point-to-point, these forms of broadcast or multicast 142 addressing MUST NOT be used. Thus the implementation MUST provide a 143 means for the operator to declare that a link is point-to-point if it 144 supports these addressing modes. Moreover, the operator is cautioned 145 that it is not always clear whether a given link is, or will remain, 146 strictly point-to-point, particularly when the link is supplied by an 147 external provider; point-to-point declarations must therefore be used 148 with care. Because of these caveats it is RECOMMENDED that 149 implementations support the procedures in Section 4 so that unicast 150 addressing can be used. 152 3. Multipoint Link Addressing 154 When a multipoint Ethernet link serves as a section [RFC5960] for a 155 point-to-multipoint MPLS-TP LSP, and multicast destination MAC 156 addressing at the Ethernet layer is used for the LSP, the addressing 157 and encapsulation procedures specified in [RFC5332] SHALL be used. 159 When a multipoint Ethernet link -- that is, a link which is not known 160 to be point-to-point -- serves as a section for a point-to-point 161 MPLS-TP LSP, unicast destination MAC addresses MUST be used for 162 Ethernet frames carrying packets of the LSP. According to the 163 discussion in the previous section, this implies the use of either 164 static MAC address configuration or a protocol that enables peer MAC 165 address discovery. 167 4. MAC Address Discovery via the G-ACh Advertisement Protocol 169 The G-ACh Advertisement Protocol (GAP) [I-D.ietf-mpls-gach-adv] 170 provides a simple means of informing listeners on a link of the 171 sender's capabilities and configuration. When used for this purpose 172 on an Ethernet link, GAP messages are multicast to the address 173 01-00-5e-80-00-0d (see [I-D.ietf-mpls-gach-adv] Section 7). If these 174 messages contain the unicast MAC address of the sender, then 175 listeners can learn this address and use it in the future when 176 transmitting frames containing MPLS-TP packets. Since the GAP does 177 not rely on IP, this provides a means of unicast MAC discovery for 178 MPLS-TP nodes without IP support. 180 This document defines a new GAP application "Ethernet Interface 181 Parameters" (TBD1), to support the advertisement of Ethernet-specific 182 parameters associated with the sending interface. The following 183 Type-Length-Value (TLV) objects are defined for this application; the 184 TLV format is as defined in [I-D.ietf-mpls-gach-adv]: 186 Source MAC Address (type = 0, length = 8): The Value of this 187 object is an EUI-64 [EUI-64] unicast MAC address assigned to one 188 of the interfaces of the sender that is connected to this data 189 link. The IEEE-defined mapping from 48-bit MAC addresses to 190 EUI-64 form is used. 192 Maximum Frame Size (MFS) (type = 1, length = 4): The Value of this 193 object is a 32-bit unsigned integer encoded in network byte order 194 that specifies the maximum frame size octets of an an Ethernet 195 Frame that can be sent over the sending interface. Where MAC 196 address learning occurs by some other means, this TLV group MAY be 197 used to advertise only the MFS. If multiple advertisements are 198 made for the same parameter, use of these advertisements is 199 undefined. 201 0 1 2 3 202 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 203 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 204 | Type=0 | Reserved | Length=8 | 205 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 206 | MAC Address in EUI-64 Format | 207 | | 208 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 210 Figure 1: Source MAC Address Object Format 212 0 1 2 3 213 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 214 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 215 | Type=1 | Reserved | Length=4 | 216 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 217 | Maximum Frame Size (MFS) | 218 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 220 Figure 2: MFS Object Format 222 Per [I-D.ietf-mpls-gach-adv], MAC Address Discovery information needs 223 to be periodically retransmitted and is to be retained by a receiver 224 based on the period of time indicated by the associated Lifetime 225 field. To expedite the initialization of a link it is RECOMMENDED 226 that a node that has been reconfigured, rebooted or is aware that it 227 have been disconnected from its peer send a GAP Ethernet Interface 228 Parameter message, and that it issues a GAP request message for the 229 Ethernet parameters at the earliest opportunity. 231 When the MAC address in the received Source MAC Address TLV changes 232 the new MAC address MUST be used (see Section 5.2 of 233 [I-D.ietf-mpls-gach-adv]). 235 If a minimum MFS is configured for a link and the MFS advertised by 236 the peer is lower than that minimum, the operator MUST be notified of 237 the MFS mismatch. Under these circumstances the operator may choose 238 to configure the LSR to shut the link, thereby triggering a fault, 239 and hence causing the end-to-end path to be repaired. Alternatively 240 the operator may choose to configure the LSR to leave the link up so 241 that an OAM message can be used to verify the actual MFS. 243 In the event a GAP message is not received within the previously 244 received associated Lifetime, the receiving node MUST assume that it 245 is now connected to a node that does not support these advertisements 246 and must behave as configured for this eventuality. 248 5. Manageability Considerations 250 The values sent and received by this protocol MUST be made accessible 251 for inspection by network operators, and where local configuration is 252 updated by the received information, it MUST be clear why the 253 configured value has been changed. The advertised information SHOULD 254 be persistent across restarts. Received advertisements MUST be 255 discarded across restarts. If the received values change, the new 256 values MUST be used and the change made visible to the network 257 operators. 259 6. Security Considerations 261 The use of broadcast or multicast Ethernet destination MAC addresses 262 for frames carrying MPLS-TP data packets can potentially result in 263 such frames being distributed to devices other than the intended 264 destination node or nodes when the Ethernet link is not point-to- 265 point. The operator SHOULD take care to ensure that MPLS-TP nodes 266 are aware of the Ethernet link type (point-to-point or multipoint). 267 In the case of multipoint links, the operator SHOULD either ensure 268 that no devices are attached to the link that are not authorized to 269 receive the frames, or take steps to mitigate the possibility of 270 excessive frame distribution, for example by configuring the Ethernet 271 switch to appropriately restrict the delivery of multicast frames to 272 authorized ports. 274 An attacker could disrupt communications by modifying the Source MAC 275 Address or the MFS values, however this is mitigated by the use of 276 cryptographic authentication as described in [I-D.ietf-mpls-gach-adv] 277 which also describes other considerations applicable to the GAP 278 protocol. Visibility into the contents of either of the TLVs could 279 provide information that is useful for an attacker. This is best 280 addressed by physical security of the links. 282 7. IANA Considerations 284 7.1. Ethernet Multicast Address Allocation 286 IANA has allocated an Ethernet multicast address from the "IANA 287 Multicast 48-bit MAC Addresses" address block in the "Ethernet 288 Numbers" registry for use by MPLS-TP LSRs over point-to-point links 289 as described in Section 2. The allocated address is 290 01-00-5E-90-00-00. IANA is requested to update the reference to 291 point to the RFC number assigned to this document. 293 7.2. G-ACh Advertisement Protocol Allocation 295 IANA is requested to allocate a new Application ID in the "G-ACh 296 Advertisement Protocol Applications" registry 297 [I-D.ietf-mpls-gach-adv] (currently located in the "Pseudowire Name 298 Spaces (PWE3)"), as follows: 300 Application ID Description Reference 301 ------------------------- --------------------------- --------------- 302 TBD1 to be assigned by Ethernet Interface (this draft) 303 IANA Parameters 305 7.3. Creation of Ethernet Interface Parameters Registry 307 IANA is requested to create a new registry, "G-ACh Advertisement 308 Protocol: Ethernet Interface Parameters" within the "Pseudowire Name 309 Spaces (PWE3)" with fields and initial allocations as follows: 311 Type Name Type ID Reference 312 ------------------ ------- ------------ 313 Source MAC Address 0 (this draft) 314 Maximum Frame Size 1 (this draft) 316 The range of the Type ID field is 0 - 255. 318 The allocation policy for this registry is IETF Review. 320 8. Acknowledgements 322 We thank Adrian Farrel for his valuable review comments on this 323 document. 325 9. References 327 9.1. Normative References 329 [EUI-64] , "[EUI64] IEEE, "Guidelines for 64-bit Global Identifier 330 (EUI-64) Registration Authority", http:// 331 standards.ieee.org/regauth/oui/tutorials/EUI64.html, March 332 1997.", . 334 [I-D.ietf-mpls-gach-adv] 335 Frost, D., Bryant, S., and M. Bocci, "MPLS Generic 336 Associated Channel (G-ACh) Advertisement Protocol", draft- 337 ietf-mpls-gach-adv-06 (work in progress), February 2013. 339 [LLDP] , "IEEE, "Station and Media Access Control Connectivity 340 Discovery (802.1AB)", September 2009.", . 342 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 343 Requirement Levels", BCP 14, RFC 2119, March 1997. 345 [RFC3032] Rosen, E., Tappan, D., Fedorkow, G., Rekhter, Y., 346 Farinacci, D., Li, T., and A. Conta, "MPLS Label Stack 347 Encoding", RFC 3032, January 2001. 349 [RFC5332] Eckert, T., Rosen, E., Aggarwal, R., and Y. Rekhter, "MPLS 350 Multicast Encapsulations", RFC 5332, August 2008. 352 [RFC5654] Niven-Jenkins, B., Brungard, D., Betts, M., Sprecher, N., 353 and S. Ueno, "Requirements of an MPLS Transport Profile", 354 RFC 5654, September 2009. 356 [RFC5960] Frost, D., Bryant, S., and M. Bocci, "MPLS Transport 357 Profile Data Plane Architecture", RFC 5960, August 2010. 359 9.2. Informative References 361 [RFC0826] Plummer, D., "Ethernet Address Resolution Protocol: Or 362 converting network protocol addresses to 48.bit Ethernet 363 address for transmission on Ethernet hardware", STD 37, 364 RFC 826, November 1982. 366 [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, 367 "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, 368 September 2007. 370 [RFC5921] Bocci, M., Bryant, S., Frost, D., Levrau, L., and L. 371 Berger, "A Framework for MPLS in Transport Networks", RFC 372 5921, July 2010. 374 Authors' Addresses 376 Dan Frost 377 Cisco Systems 379 Email: danfrost@cisco.com 381 Stewart Bryant 382 Cisco Systems 384 Email: stbryant@cisco.com 386 Matthew Bocci 387 Alcatel-Lucent 389 Email: matthew.bocci@alcatel-lucent.com